The act of once finishing a sexual partner in a bathroom, you announce you will return shortly, further proceeding to lock the doors, trapping your partner (victim). After this you immediately gas the bathroom, killing your partner.
"Ya boi just Dachau'd that bitch son!"
"Hey I totally hate that bitch, so I'll just Dachau her tonight!"
"I've finally ended things with Lisa after Dachauing her yesterday!"